Prince Andrew remains "fully committed" to his role promoting British trade abroad, Buckingham Palace has said in response to fresh speculation about his contacts with disgraced foreign regimes.

The comments came as government ministers rallied to the prince's aid. The foreign secretary, William Hague, declared that the prince retained his confidence in supporting the work of UK Trade & Investment (UKTI), the organisation which helps British companies sell products overseas.

The prince has been criticised for entertaining Sakher el-Materi, the ousted Tunisian dictator Zine al-Abidine Ben Ali's son-in-law, to a lunch at Buckingham Palace last October, triggering calls for him to renounce his trade promotion role.

Speaking on the BBC's Politics Show on Sunday, however, Hague insisted: "I've seen a lot of benefits that [Prince Andrew] has brought in in countries that I have visited where he's been performing that role.

"I'm not an expert on [any of his] embarrassments, I haven't had time, with everything going on in the Middle East, to look at those things. But certainly I've seen around the world a lot of good that he has done for this country."

On Sunday, Buckingham Palace issued a statement saying: "The prince remains fully committed to his role as special representative and it's understood that the government backs him on this point."

Last week the anti-monarchy group Republic formally lodged a complaint with UKTI, calling for an investigation into allegations relating to Prince Andrew.

The organisation has raised concerns about "his friendship with the convicted sex offender Jeffrey Epstein" and links to the Gaddafi regime in Libya.

A spokesman for Republic, Graham Smith, said: "It is clear that the continued speculation about the duke's friendships, business interests and professional conduct risks bringing UKTI, the Department for Business and the Foreign Office into disrepute."